Wide area lighting fixtures are commonly used for both indoor and outdoor applications. Indoor lighting such as those used in arenas, gymnasiums, aircraft hangers, and other large spaces use wide area lighting. Outdoor lighting fixtures, such as those used for street lighting, parking structures, loading dock areas, and other exterior lighting applications, also use wide area lighting and may be known in such applications as canopy lights. These wide area fixtures typically involve a light source, such as a bulb, lamp, or other illumination source, a transformer for converting a power supply to the light source's power requirements, and a reflector and/or lens system to direct the light output from the light source into a desired illumination pattern. When the fixtures are elevated and their light output directed downward, a wide area can be illuminated by strategic placement of the fixtures.
The types of wide area lighting fixtures vary depending upon the particular application and lighting requirements, as do the light sources employed. High Intensity Discharge (“HID”) fixtures, for example, are one of the most prevalent outdoor lighting fixtures in use today and may include metal halide, high pressure sodium, and low pressure sodium light sources. As an example, metal halide lamps produce approximately 70-115 lumens per Watt with operating life expectancies approximately in the 5,000-20,000 hour range. By comparison, high pressure sodium lamps produce about 50-140 lumens per Watt on average with an operating life expectancy of approximately 24,000-40,000 hours. Maintaining these types of fixtures can be expensive due to the cost of the replacement light sources themselves and the labor and equipment (e.g., boom trucks, lane flashers to rear, caution area markers, etc.) needed to reach the fixtures, which are often in difficult to reach locations, and to disassemble them to replace the proper component.
Another type of light source used for wide area lighting is induction lighting. Induction lighting is similar to fluorescent lighting in that induction lighting uses the excitation of a contained gas or gases, which react with phosphors inside a lamp to produce white light. However, induction lamps excite the gases using a magnetic field, as opposed to electrodes as in fluorescent lighting. Induction lamps are rated up to 100,000 hours operating life and, consequently, are typically employed where maintenance of the lamp is problematic. Moreover, induction lamps are energy efficient, typically operating at greater than 85 lumens per Watt. Further, induction lamps exhibit high lumen maintenance over the entire life and provide instant on and instant restrike capability, such that there is virtually no warm up time.
Yet another type of light source used for wide area lighting is the light-emitting diode (“LED”) array. The efficacy of LEDs, as measured in lumens per Watt, is rapidly evolving, and more powerful LEDs are being released every 6-12 months. Currently, LEDs are approaching efficacies of 130 lumens per Watt with a rated operating life of 50,000-100,000 hours. However, individual, discrete LEDs do not produce sufficient light output to illuminate a wide area. As a result, to produce sufficient illumination in most applications, prior art solid-state lighting systems utilize many LEDs, such as clusters of LEDs arranged in arrays on printed circuit boards. However, these clusters create significant heat that can build up and damage the LEDs unless the heat is controlled and dissipated. Consequently, most LED lighting manufacturers mount the LEDs to large, heavy heat sinks. If an individual LED malfunctions it is not efficiently replaceable and cannot be simply unscrewed and replaced as with other types of light sources. Furthermore, as newer, brighter, higher efficacy LEDs come on the market, the entire prior art LED array requires replacement, and likely a complete heat sink redesign, because the supporting heat sink system is most often constructed as a single integrated unit. Today, few modularized lighting systems are available that allow for upgrades to the newest LED technology without completely developing new components for the entire system. Consequently, there is significant expense in both materials and labor to either replace a non-LED fixture with one incorporating LEDs or to upgrade a current LED fixture to the latest technology, as it will generally require an entirely new LED array and heat sink system designed to handle a new and more powerful LED.
Accordingly, a need exists for a modular convertible lighting fixture that can be easily and effectively converted to use one of multiple high-efficiency light sources by replacing only the light source and associated electronics without the need to completely remove the fixture from its mounted location. Further, there is a need for a convertible lighting fixture that is easily and cost-effectively maintained and upgraded to the latest high-efficiency lighting technology without replacing the entire fixture.